I've decided to send off my older photos to be scanned. I'm a little nervous about it but right now they are just sitting in boxes - realistically, I'm not going to scan them myself or put them in albums. I'm willing to take the risk in order to get them in a more usable form.

Anyway, my question is, what's the best way to package them up for shipping? I have a mix of 3x5 and 4x6 prints, lots of prints from 110 film, and a large collection of polaroids. Mostly from the 70's and 80's. Some of the prints are currently in those old style "magnetic" albums so I'm nervous the pictures will stick together if I don't package them correctly.

The scanning service really gave no guidance other than to send them in stacks. Maybe I'm overthinking this, but does anyone have suggestions?

Also, if I want to write on the backs to identify where the photos came from, is there a way to do it that will be safe? (A pencil, perhaps?)